Organic Interlayer for Enhanced Buried Interfaces in Wide-Bandgap Perovskite Solar Cells

Achieving high performance and stability in wide-bandgap perovskite solar cells (PSCs) is essential for the development of tandem solar cells capable of surpassing the theoretical efficiency limit of single-junction photovoltaic (PV)devices. However, the performance of wide-bandgap PSCs remains challenging, primarily due to nonradiative recombination at the interfaces. An interlayer applied at the buried interface between the hole transport layer and the perovskite in a p-i-n architecture can play a pivotal role, as it is critical for efficient charge transport, extraction, and the formation of high-quality perovskite films. In this work, a donor-acceptor architectural quinoxaline-based organic interlayer specifically designed for the interface between NiO_x and wide-bandgap perovskite is introduced. The incorporation of this interlayer effectively passivates defects at the perovskite interface, leading to improved charge carrier extraction and a substantial reduction in nonradiative recombination, while also enhancing the overall quality of the perovskite film. Moreover, the high dipole moment of QxNN increases the built-in potential of the device, further contributing to enhanced charge extraction. Notably, PSCs incorporating the organic interlayer exhibit a remarkable increase in power conversion efficiency, from 17.5% to 20.0%, while maintaining their performance over 500-h under ambient conditions.